Radiating termination for a rhombic antenna



g- 50' K. POSTHUMUS 2,517,238

RADIATING TERMINATION FOR A ammo ANTENNA Filed April 22. 1946 IRAJYWITTER.

KLAA 5 2051710114 US.

I N V EN TOR.

ATTORNEY.

Patented Aug. 1, 1950 RADIATING TERMINATION FOR A RHOMBIC ANTENNA Klaas Posthumus, Eindhoven, Netherlands, as-

signor, by mesne assignments, to Hartford National Bank and Trust Company, Hartford,

Conn as trustee Application April 22, 1946, Serial No. 663,820

In the Netherlands October 22, 1942 Section 1, Public Law 690, August 8,1946 .1

Patent expires October 22, 1962 Claims.

This invention relates to an aerial system in which for example for the directional transmission of oscillations to be transferred use is made of a rhombic aerial in which only travelling waves must occur. The occurrence of stationary waves is avoided in such an aerial or in other aerial systems in which solely travelling waves must occur by'terminating the end of the aerial system that is remote from the supply end by with the surge resistance of the aerial system.

It has been suggested before to increase the efficiency of such an aerial system by constituting the terminating res stance by a second aerial system formed by a dipole antenna which by means of a transmission line is connected to the termi nating end of the former aerial system and is so arranged that the radiations of the two aerial systems are backed up by one another.

The last-mentioned system,.however, exhibits an undue intense variation with the frequency of the oscillations to be transferred or received. The invention has for its object to avoid this intense variation with frequency.

According to the invention, for this purpose the second aerial system is arranged in the immediate proximity of theterminating end of the former aerial system and the ends of the former aerial system are connected direct to the input terminals of the second aerial system.

Thus, a suitable relative arrangement of the two aerial systems avoids the use of the transmission line which otherwise would be required for the interconnection of the systems and thus the undue intense variation of the entire system with frequency is avoided.

If the invention is used with a rhombic aerial terminated by a dipole it is favourable to cross the sides of the rhombic aerial connected to the dipole aerial and constitute the dipole aerial by a single conductor extending between the termihating ends of the rhombic aerial. This does away with the need for earthing the free ends of the dipole halves.

In order to get in the latter case to a symmetric figure of the rhombic aerial, desired in View of the radiation diagram, the sides of the rhombic aerial that are connected to the feeder are, preferably crossed similarly to the other sides and the feeding ends of these sides are respectively connected with the feeder by two conductors jointly constituting a dipole antenna.

In order that the invention may be clearly understood and readily carried into eifect it will now be described more fully with reference to means of an impedance whose value corresponds the accompanying drawing, in which Figures 1 to 3 show aerial systems according to the invention, the former aerial system being formed by an ordinary rhombic aerial, an asymmetric rhombic aerial or a symmetrically crossed rhombic aerial respectively.

In the form of construction shown in Figure 1 the former aerial system comprises a rhombic aerial I which is situated for example in a horizontal plane and which is constituted by two conductors 2, 2' having a length of, say, 4%, if x is the wavelength of the oscillations transmitted. The connecting terminals ofthe rhombic aerial l situated on the right hand side are connected to a transmitter {whereas the conductors 2, 27 are connected at the left hand ends 5 and 5' respectively (terminating ends) with conductors 6, 6 each having. a length of Mn, which are earthed at the free end and jointly constitute a dipole antenna having an input resistance corresponding to the surge resistance of the rhombic aerial. a a i By a proper choice of the angle formed by the conductors 2,601 2, B." respectively this dipole is so arrangedthat the main directions of radiation coincide forboth aerial systems in accordance with the direction denoted by an arrow 1.

As shown in the figure, the second aerial. 6, 1601s arranged in the immediate proximity of the terminating ends 5, 5 of the rhombic aerial and the two aerial systems are interconnected direct i. e. without the use of a transmission line serving for the connection.

In the form of construction of the aerial system shown in Figure l earthing the free ends of the dipole halves often entails difliculty.

These difficulties may be obviated by the use of the form of construction shown in Figure 2. In this case, the sides of the rhombic aerial I that are connected to the dipole aerial are crossed and this permits of the dipole halves being so arranged that the free ends are adjacent each other and thus can be connected direct. This does away with the necessity of earthing the free ends.

In order to ensure a symmetric structure of the rhombic aerial as before the form of construction shown in Figure 3 may be used. In this case, the sides of the rhombic aerial that are connected to the feeder are crossed similarly to the other sides and are connected to the feeder by two conductors 8, 8 respectively which jointly form a dipole aerial, as before, each having a length of AA. The radiation diagram of the rhombic aerial thus obtained corresponds with 3 that of a normal rhombic aerial of similar form and dimensions Without crossed. sides.

In the forms of construction illustrated. the former aerial system is terminated each time by a second aerial system formed by a dipole constituted by two wires having a length of /41. Obviously, however, other known aerials may also be used to constituted the second aerial system. Thus, for example, each of, the conductors. of the rhombic aerial may be connected to a radiator having a length of &1 or else for example conical aerials may be used to constitute the second aerial system, the latter being eminently suitable for the present object in view of their frequency-impedance characteristic curve which has a substantially flat course for a wide frequency band.

What I claim is:

1. An aerial system comprising a rhombic an-= tenna constituted by a pair of conductors, means for energizing said system connected to the terminals of said conductors disposed at one end thereof and a dipole radiator operatively conneeteddirectly to the terminals of said conductors disposed at the other end thereof, all elements of said system following the terminals at said one end of said conductors being radiating elements.

2. An aerial system comprising a rhombic antenna constituted by a pair of conductors, means for energizing said system connected to the terminals of said conductors disposed at one end thereof, and a dipole radiator having its inner terminals connected directly to the terminals of said conductor disposed at the other end thereof and its outer terminals grounded, all elements of said system following the terminals at said one end of said conductors being radiating elements.

3. An aerial system comprising a rhombic antenna constituted by a pair of V-shaped conductors, said conductors at one. end thereof being crossed, a dipole radiator having its outer terminals directly connected to the terminals of said conductors disposed at said one end thereof and itsinnerterminals interconnected, and means for energizing said aerial system connected to the terminals of said conductors disposed.v at the otherend thereof, all elements of said system following the terminals of said conductors disposed at'said other end thereof beingradiating elements.

1. An aerial system comprising a rhombic an tenna constituted by a pair of V-shaped conductors, said conductors at one end thereof being crossed, a radiating member whose length is substantially equal to a half-wavelength of the operating frequency of said system, said member being directly connected between the terminals of said conductors at said one end thereof, and means for energizing said system connected to the terminals of said conductors disposed at the other end thereof, said member acting as a dipole, all elements of said system following the terminals at said other end of said conductors being radiating elements.

5. An aerial system comprising a rhornbic antenna constituted by a pair of V-shaped conductors and symmetrically arranged so that said conductors are crossed at both ends thereof, a pair of dipole radiators, the outer terminals of one of said radiators being connected directly to the terminals of said conductors disposed at one end thereof and the inner terminals of said. one of said radiators being interconnected, the outer terminals of the other of said radiators being con.- nected directly to the terminals. of said conductors disposed at the other end thereof, and means for energizing said system connected to the inner terminals of said other of said radiators, all elements of said system following the terminals of said conductors disposed at said other end thereof being radiating elements.

KLAAS POSTHUMUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,126,295 Warren Aug. 9, 1938 2,131,108 Lindenblad Sept. 27, 1938 2,151,159 Brown May 9, 1939 2,297,925 Usselman Oct. 6, 1942 2,366,195 Kandoian Jan. 2, 1945 2,379,260 Sprague June 26, 1945 FOREIGN PATENTS Number Country Date 833,529 France June 15, 1937 

